U.S. patent number 4,177,183 [Application Number 05/789,660] was granted by the patent office on 1979-12-04 for process for the preparation of coatings composed of polyhydroxy compounds.
This patent grant is currently assigned to Hoechst Aktiengeselischaft. Invention is credited to Horst Dalibor.
United States Patent |
4,177,183 |
Dalibor |
December 4, 1979 |
**Please see images for:
( Certificate of Correction ) ** |
Process for the preparation of coatings composed of polyhydroxy
compounds
Abstract
The subject of the invention is a process for the production, by
shaping while removing the solvent, of coatings composed of
polyhydroxy compounds based on copolymers which contain hydroxyl
groups and which are reaction products from mixtures of
polymerizable vinyl compounds which contain .alpha.,
.beta.-ethylenically unsaturated monocarboxylic or dicarboxylic
acids and styrene, or derivatives thereof, and of glycidyl esters,
as well as polyisocyanates in solvents which do not contain active
hydrogen atoms.
Inventors: |
Dalibor; Horst (Norderstedt,
DE) |
Assignee: |
Hoechst Aktiengeselischaft
(DE)
|
Family
ID: |
5976598 |
Appl.
No.: |
05/789,660 |
Filed: |
April 21, 1977 |
Foreign Application Priority Data
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Apr 29, 1976 [DE] |
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2618810 |
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Current U.S.
Class: |
524/317; 428/463;
428/423.1; 524/364; 524/507; 525/125; 525/193 |
Current CPC
Class: |
C08G
18/6258 (20130101); C09D 133/14 (20130101); C08K
5/29 (20130101); C08K 5/29 (20130101); C08L
33/14 (20130101); C09D 133/14 (20130101); Y10T
428/31551 (20150401); Y10T 428/31699 (20150401); C08L
2666/36 (20130101) |
Current International
Class: |
C08G
18/62 (20060101); C09D 133/14 (20060101); C08G
18/00 (20060101); C09D 003/74 (); C09D
003/52 () |
Field of
Search: |
;260/31.4,77.5CR,836GL,18EP,21,32.8R,856,859R ;526/49,16
;528/46 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1556309 |
|
Dec 1960 |
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FR |
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1390572 |
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Jan 1965 |
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FR |
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Primary Examiner: Pertilla; Theodore E.
Attorney, Agent or Firm: Hueschen; Gordon W.
Claims
I claim:
1. A coating binder composition, dissolved in solvents which do not
contain active hydrogen atoms, composed of a binder (A) comprising
a mixture of a copolymer which contains hydroxyl groups and which
is a reaction product from mixtures of polymerizable vinyl
compounds which contain .alpha.,.beta.-ethylenically unsaturated
monocarboxylic acids and styrene and glycidyl esters and (B),
polyisocyanate wherein component A consists of 60-80 percent by
weight of hydroxyl group containing copolymers, having a total
hydroxyl group content of 3.5 to 6.5 percent by weight, prepared in
the presence of a mixture of a diacyl peroxide or perester and an
alkyl hydroperoxide or dialkyl peroxide as polymerization
initiators, from:
(a) 5-24 percent by weight of glycidyl ester of
alkanemonocarboxylic acids selected from the group consisting of
.alpha.-alkyl-alkanemonocarboxylic acids and
.alpha.,.alpha.-dialkylalkanemonocarboxylic acids of the following
empirical formula C.sub.12-14 H.sub.20-26 O.sub.3, and slow,
uniform addition to said glycidyl esters (a) of
(b) 12-30 percent by weight of compounds selected from the group
consisting of hydroxyethyl acrylate and hydroxyethyl
methacrylate,
(c) 1-10 percent by weight of acrylic acid,
(d.sub.1) 20-50 percent by weight of styrene, and
(d.sub.2) 5-35 percent by weight of methyl methacrylate,
the components a, b, c, d.sub.1, and d.sub.2, based on 100 percent
by weight of components a to d.sub.2, and the polymerization and
condensation reactions taking place simultaneously and jointly,
with the additional condition that components a, b, and c are
employed in such quantities that the copolymer component A has a
hydroxyl group content of 3.5 to 6.5 percent by weight, and
component B consists of 20 to 40 precent by weight of an organic
polyisocyanate, it being necessary that components A and B together
give a numerical value of 100 percent by weight.
2. A composition according to claim 1, wherein component A contains
63 to 68 percent by weight of the copolymers which contain hydroxyl
groups and component B contains 32 to 37 percent by weight of an
organic triisocyanate which has been obtained by reacting 3 mols of
hexamethylene diisocyanate and 1 mol of water, it being necessary
that A and B together give a numerical value of 100 percent by
weight.
3. A composition according to claim 1, wherein 1 to 10 percent by
weight of reactive melamine resins, relative to the weight of the
binder component, are used as an additional binder.
4. A composition according to claim 1, wherein component A is a
solution containing 10 to 30 percent by weight of inert organic
solvents which are customary in the lacquer industry and 70 to 90
percent by weight of copolymers, it being necessary that the
percentages of components A and B add up to 100 percent by
weight.
5. A coating composition according to claim 1, wherein component A
comprises a copolymer which has a hydroxyl group content of
4.5.+-.0.3 percent by weight and which component A copolymer is
obtained from a mixture consisting of
A"--20-25 percent by weight of ethylglycol acetate and
B"--75-80 percent by weight of a reaction mixture of the components
a to d.sub.2 :
(a) 11-12 percent by weight of glycidyl ester of
.alpha.,.alpha.-dialkylalkanemonocarboxylic acids of the following
empirical formula C.sub.13 H.sub.24 O.sub.3 which have been
obtained by reacting tripropylene, carbon monoxide and water and
which consist essentially of monocarboxylic acids with highly
branched C.sub.10 chains, being heated with the ethylglycol acetate
to 165.degree. to 170.degree. C., and a mixture consisting of
(b) 25-26 percent by weight of compounds selected from the group
consisting of hydroxyethyl acetate and hydroxylethyl
methacrylate,
(c) 3-4 percent by weight of acrylic acid,
(d.sub.1) 44-48 percent by weight of styrene,
(d.sub.2) 10-16 percent by weight of methyl methacrylate,
(e) 2-2.5 percent by weight of tert.-butyl perbenzoate, and
(e') 1-1.5 percent by weight of cumene hydroperoxide,
dissolved to form an 80 percent strength solution in a mixture of
alcohols, ketones and cumene,
it being necessary that the sum of the monomers a to d.sub.2 add up
to 100 percent by weight, said reaction mixture B" being added
slowly and uniformly to component A" in the course of 6 to 10 hours
and the temperature of said mixture A" plus B" being kept at
170.+-.5.degree. C. in the course thereof, until the solids content
of the solution has reached a value of 80.+-.1 percent by weight,
the polymerization and condensation reactions taking place jointly
and simultaneously and the copolymer having a hydroxyl group
content of 4.5.+-.0.3.
6. A coating composition according to claim 5, wherein compound a
of component B" is a mixture of glycidyl esters of
.alpha.,.alpha.-dialkylalkanemonocarboxylic acids having up to
about 10 percent by weight of glycidyl ester of
.alpha.,.alpha.-dialkylalkanemonocarboxylic acids of the said
empirical formula, the mixture having an epoxide equivalent of 240
to 250.
7. A coating composition according to claim 1, applied to a
sheet-like structure, and from which composition so applied,
solvents are removed by air drying.
Description
BACKGROUND OF THE INVENTION
(1) Field of the Invention
It is an object of the present invention to provide a process for
the manufacture of coatings, wherein the sheet-like structures
which can be manufactured therefrom have considerably improved
properties in various ways. This includes the property that a
lacquer which is applied to a metallic substrate and which contains
the copolymer solution in combination with organic polyisocyanates,
should, after drying in air for three to four days at temperatures
of about 20.degree. C., cure in such a way that the film no longer
swells under the influence of water and also cannot be removed
mechanically by scratching, even if the film is exposed to water
for brief periods at temperatures of 50.degree.-70.degree. C.
It is also a further object of the present invention that the
copolymer solutions which are present in the reactive lacquer
should, in combination with other copolymer solutions which are
synthesised, as thermoplastic copolymers, on the basis of lower
alkyl methacrylates and acrylic acid or methacrylic acid, permit
the manufacture of coating agents which are free from
polyisocyanates and which dry at room temperature in a physical
manner by solvent evaporation to give films having outstanding
properties.
It is a further objective of the present invention to use, in the
reactive lacquer, an acrylic resin, containing hydroxyl groups, of
a type which, in combination with polyisocyanates provides the
binder foundation for air-drying lacquers and stoving lacquers
which are suitable for use in the automobile industry as top
lacquers, the lacquer being present after stoving in layer
thicknesses of about 40 to 80 .mu.m and the top lacquer being
located directly on top of the stoved primer of electro-dip
lacquer.
In the present-day modern methods for painting motor vehicles in
the automobile factory, the coachwork parts are usually coated,
after phosphating, with a primer of electro-dip lacquer and this is
stoved to give a plastic coating. A sprayed lacquer or a coating
composition, which is generally designated as a filler, is then
applied to this plastic coating, usually by a spray process, and
stoving is carried out once more.
The pigment-containing automobile lacquer formulation is then
applied, in the desired pigmentation, by spraying onto this
two-coat lacquering or primer and the coachwork is stoved
again.
The total coating, which, as explained above, consists of three
layers, has a layer thickness of 70-100 .mu.m after stoving, the
proportion relating to the outer layer of top lacquer being 30 to
40 .mu.m. In the course of methods of rationalisation in the
automobile industry, efforts are being made to change over from the
three-layer system to a two-layer structure. In this, the
electro-dip coat of lacquer or an equivalent other undercoating
should form the first coating layer and after this, the final coat
of lacquer with the pigment-containing lacquer should be built up,
but the total thickness of the layers applied should have, in
total, the same layer thickness. Using the conventional automobile
top lacquers, it is, however, not possible, with the customary
spraying and stoving treatment, to produce such coatings from
pigment-containing lacquer formulations which, after drying in air
or after stoving, give lacquer films which are completely uniform
(that is to say free from the so-called sagging and free from
craters and blisters).
In addition, the copolymers employed according to the invention,
and also the combinations of coating agents consisting of the
copolymers and the polyisocyanates, should be miscible and
compatible with thermoplastic copolymers which are soluble in
organic solvents. The use of thermoplastic copolymers makes
possible rapid drying, especially when used as a repair lacquer to
touch-up defects in painting. Tack-free drying in 5 to 10 minutes
at room temperature is required in such cases and the desired
resistance to premium motor fuels is achieved by means of the new
binder combinations after a drying time of as little as one
hour.
A further particular advantage consists in the fact that, for
example, it is also possible to touch-up in a partial manner a
painted automobile body after final assembly, on which defects in
painting still have to be touched-up and the reactive lacquer which
is applied consists of a combination of binders composed of the
copolymers used according to the invention and polyisocyanates. The
touching-up can be carried out on the partially or completely
crosslinked combinations of binders. In the combinations of binders
which are envisaged as the touching-up lacquer and which are
composed of 20 to 80% by weight, preferably 40 to 60% by weight, of
the copolymers used according to the invention and 80 to 20% by
weight, preferably 60 to 40% by weight, of thermoplastic
copolymers, no differences in colour shade are evident between the
partially or completely cross-linked reactive lacquer and the
touching-up lacquer, provided that the same pigments are employed,
in terms of quantity and type.
In addition, the copolymer solutions used according to the
invention, which are of lower viscosity, display a better
absorption of pigment, both when using inorganic pigments, such as,
for example, titanium dioxide, or when using organic pigments, such
as, for example, carbon black. When titanium dioxide is used as the
pigment, the copolymers which are used according to the invention,
and also the reactive lacquer manufactured therefrom, still give
films of high gloss at a pigment/binder ratio of 1.5 to 2:1, while
the known copolymers and the known reactive lacquers manufactured
therefrom, exhibit a marked falling-off in gloss at the same level
of pigmentation. In addition, it has been found that the copolymers
used according to the invention and the reactive lacquers
manufactured therefrom give lacquers of high gloss with carbon
black, while the known copolymers and the reactive lacquers
manufactured therefrom exhibit matt films at the same level of
pigmentation.
It is a further object of the invention to use soluble organic
copolymers which are present as a solution having a solids content
of 70 to 90% by weight, the copolymer solutions which are
formulated ready for spraying having, at 25.degree. C., a viscosity
of 25 seconds, measured in a DIN cup having a 4 mm flow orifice,
and a solids content of 40 to 65% by weight, preferably 45 to 65%
by weight. Thus, the copolymer solutions used according to the
invention take account of the requirements, set by environmental
protection, for binders of high solids content and low solvent
content.
The outstanding advantage of the copolymer solutions which are
present in accordance with the invention in the reactive lacquer
resides in the fact that it is possible for the hydroxyl groups in
the copolymers to crosslink with polyisocyanates at room
temperature and also at elevated temperatures and to produce, in
the clear lacquer, lacquers of high solids content, in the
condition formulated ready for spraying, with a viscosity of 40
seconds, measured at 25.degree. C. in a DIN cup having a 4 mm flow
orifice, and a solids content of 61 to 80% by weight, preferably 65
to 80% by weight.
(2) Prior Art
Numerous suggestions to manufacture solvent-resistant and
alkali-resistant lacquers by reacting polyisocyanates and
copolymers containing hydroxyl groups, and to process the lacquers
to give coatings, have been disclosed. DT-AS 1,247,006 describes a
process for the manufacture, by the polyisocyanate polyaddition
process, of alkali-resistant sheet-like structures which are
obtained from polyisocyanates and copolymers containing hydroxyl
groups, but which are not adequately stable to water after a
reaction time of three to four days at 20.degree. C. These
coatings, obtained by this known process, are, therefore, not
suitable as top lacquers for external coats of lacquer which are
resistant to weathering, since blistering occurs after a very short
time and the adhesion of the lacquer to the various metallic
substrates falls off and the lacquer thereby comes away from the
substrate.
It is also known that polyhydroxy compounds of polyols and
polyisocyanates must be cured in order to obtain crosslinked
lacquer coatings having good resistance properties. These
combinations also display too low a resistance to water and a lower
resistance to weathering in the cured lacquer coatings.
French Pat. Specification No. 1,556,309 describes a coating agent
which contains solvent and, as the film-forming constituents:
A. a copolymer consisting of
(1) 2-50 parts by weight of an addition product in the ratio 1:1,
of a carboxyl group of an .alpha.,.beta.-ethylenically unsaturated
acid and an epoxide group of a glycidyl ester of an aliphatic
carboxylic acid which contains tertiary C atoms and in which the
aliphatic tertiary group contains 4-26 C atoms, and
(2) 98-50 parts by weight of unsaturated, copolymerisable monomers,
the total quantity of (1) and (2) adding up to 100 parts by weight,
and
B. at least one polyisocyanate which contains at least 2 isocyanate
groups per molecule, the polyisocyanate being present in relation
to the copolymer in a quantity of 0.2-5 equivalents, relative to
the hydroxyl groups of the copolymer.
As the examples of this French patent specification show, copolymer
solutions are obtained which have a solids content of only 48 to
52%. The content of hydroxyl groups in Examples 1 to 10 is 0.8 to
3.18% by weight in the known copolymers.
In Example 1=0.8% of hydroxyl groups
in Example 2=1% of hydroxyl groups
in Example 3=1.26% of hydroxyl groups
in Example 4=1.52% of hydroxyl groups
in Example 5=1.41% of hydroxyl groups
in Example 6=1.41% of hydroxyl groups
in Example 7=1.66% of hydroxyl groups
in Example 8=1.85% of hydroxyl groups
in Example 9=1.85% of hydroxyl groups
in Example 10=3.18% of hydroxyl groups.
If the procedure indicated in French Pat. Specification No.
1,556,309 is then followed, and as the content of hydroxyl groups
in the copolymers is increased, the viscosity also increases. On
diluting with xylene to a viscosity of 25 seconds at 25.degree. C.,
measured in a DIN cup having a 4 mm flow orifice, the solids
content of the copolymer solutions also decreases.
It cannot, however, be inferred from French Pat. Specification No.
1,556,309 that the selection of specified solvents and a specified
quantity range of a combination of different polymerisable monomers
and the use of a combination of initiators makes it possible to
manufacture copolymer solutions which have a substantially higher
solids content and which establish the use of the new copolymers as
binders for lacquer systems which are based on acrylates and have a
low solvent content.
The particular advantage of the copolymer solutions used according
to the invention consists in the fact that, if the content of
hydroxyl groups in the copolymers is increased, the viscosity
falls. On diluting with xylene to a viscosity of 25 seconds at
25.degree. C., measured in a DIN cup having a 4 mm flow orifice,
the solids content of the copolymer solutions used according to the
invention increases.
It is found, surprisingly, that the copolymers which are used
according to the invention and which have a hydroxyl group content
of 3.5 to 6.5, preferably 4.5 to 5.5, % give lower viscosities than
the known copolymers which have the same hydroxyl group content.
Thus, when dissolved at 70% strength by weight in ethylglycol
acetate, the copolymer solutions used according to the invention
have viscosities of U to Z.sub.4, preferably X to Z.sub.3, measured
by the Gardner-Holdt method at 20.degree. C. Proof of this
statement is given by a comparison between the copolymer solution 1
(A) used according to the invention and the known comparison
copolymers 3 and 4. As 70% strength by weight solutions in
ethylglycol acetate, the comparison copolymers 3 and 4 give higher
viscosities which are higher than Z.sub.6, measured by the
Gardner-Holdt method at 20.degree. C.
Compared with the known copolymers, the copolymers used according
to the invention exhibit, in the combination with polyisocyanates,
the following advantages: better resistance to solvents, higher
abrasion resistance and better resistance to weathering in the
climate of Florida. In addition, in the combination with
polyisocyanates, the copolymers used according to the invention
produce, when diluted with acetone, xylene or butyl acetate to a
viscosity of 40 seconds at 25.degree. C., measured in a DIN cup
having a 4 mm flow orifice, lacequers of a higher solids content
which have a solids content in the clear lacquer of 61 to 80% by
weight, preferably 65 to 80% by weight. When such clear lacquers or
pigmented lacquers are applied by spraying to sheet steel, dry film
layers of high thicknesses of 70 to 80 .mu.m which do not exhibit
crater formation and blistering, are obtained after a brief period
of exposure to air and subsequent stoving.
The known lacquer combinations, which are described in French Pat.
Specification No. 1,556,309, only give a solids content of 10 to
60% by weight in the clear lacquer when diluted with acetone, butyl
acetate or xylene to 40 seconds at 25.degree. C. When such clear
lacquers or pigmented lacquers are applied by spraying to sheet
steel, dry film layers of lower thicknesses of 40 to 50 .mu.m which
also still exhibit crater formation and blistering, are obtained
after a brief period of exposure to air and subsequent stoving.
French Patent Specification 1,390,572 describes a process for the
manufacture of copolymers in which an .alpha.,.beta.-unsaturated
carboxylic acid or one of its derivatives is copolymerised in a
solvent with one or more other vinyl monomers in the presence of a
catalyst, and simultaneously or successively the reaction product
is reacted with a glycidyl ester of the formula: ##STR1## in which
R is an aliphatic or aromatic radical which can also be substituted
and which is either saturated or contains one or more ethylenically
unsaturated bonds.
As the examples of French Pat. Specification No. 1,390,572 show,
the copolymers contain, in addition to styrene, several acrylates
or mixtures of acrylates and methacrylates or several
methacrylates. In addition, it is mentioned under the letter D in
the summary of this French patent specification that the copolymers
described in that text can be used for coating agents which have
been obtained by co-mixing with an isocyanate prepolymer or a
polyisocyanate. The coating agents of the type described in that
text also display, after curing, a relatively high elasticity and
are therefore still capable of being attacked by solvents.
In the book "Lackkunstharze" ("Synthetic Resins for Lacquers") by
H. Wagner and H. F. Sarx, Carl Hanser Verlag, Munich 1959, it is
stated on page 170, paragraph 1, that monomers which produce very
hard homopolymers, such as vinyl chloride, styrene et cetera, are
copolymerised with monomers which, for their part, produce very
soft homopolymers, such as acrylic acid butyl ester, vinyl isobutyl
ether et cetera. As well as a change in the solubility, the
resulting products exhibit a particularly advantageous film
elasticity. In this case, one speaks of "internal plasticisation"
of the hard film-formers. However, it is not evident from these
data how the object of the present invention can be achieved in
practice. In the book "Paint and Varnish Technology" by William v.
Fischer, Verlag Reinhold, New York, 1948, page 222, paragraph 2,
the properties of acrylic resins and methacrylic resins are
described as generally thermoplastic and very variable between
soft, tough semi-liquids and compact, hard solids, and are
characterised by colourless transparency and excellent aging
properties as well as the capacity to resist sunlight, oxygen and
ozone, the properties of the acrylates and methacrylates depending
on the molecular weight of the polymers. It is also stated that it
is possible to make large variations in the properties of the
polymers by increasing the temperature of polymerisation and the
concentration of catalysts in the solvent used for polymerisation
and by varying the copolymers, and that it is possible to
manufacture synthetic resins having any degree of flexibility, as a
result of which the simultaneous use of plasticisers is dispensed
with. It cannot, however, be inferred from these general data how
the object of the present invention can be achieved in
practice.
In the brochure "Plexigum, Plexisol, Plexalkyd, Plextol, Rohagit,
Acriplex; Eigenschaften, Unterschiede und Beziehungen zueinander"
("Plexigum, Plexisol, Plexalkyd, Plextol, Rohagit and Acriplex;
Properties, Differences and Relationships with one another") of
Messrs. Rohm & Haas GmbH, Darmstadt, 1963 range of products, it
is stated on pages 6 and 7 that polyacrylic esters and
polymethacrylic esters are distinguished by the following
properties: they are colourless and clear, stable to light, stable
against yellowing, even at high temperatures, extremely stable
against weathering and aging, outstandingly stable to chemicals and
physiologically harmless. The individual polymers differ chiefly in
mechanical properties and in solubility. The following is
applicable here:
1. The hardness falls off as the number of carbon atoms in the
alcohols used for esterification increases.
2. Branched alcohols produce harder polymers than linear alcohols
(poly-n-butyl methacrylate and poly-isobutyl methacrylate).
3. Polymethacrylic acid esters are harder than polyacrylic acid
esters. However, it is not evident from these general statements
either how the object of the present invention could be
achieved.
Copolymers which contain hydroxyl groups and which are synthesised
from mono-ethylenically unsaturated monomers and have an acid
number of up to 40 and contain at least 5 percent by weight of
ethylenically unsaturated carboxylic acid units having active
hydrogen atoms and which have a structure composed of selected
groupings consisting of ##STR2## wherein R is a tertiary, aliphatic
hydrocarbon radical having the structure ##STR3## wherein R.sub.1
represents -CH.sub.3 and R.sub.2 and R.sub.3 represent alkyl groups
having 1 to 12 carbon atoms, the mono-ethylenically unsaturated
monomers being, in accordance with claim 6, styrene and acrylic
acid and the polymer having an acid number of 5 to 40, have already
been described in U.S. Pat. Specification No. 3,330,814. These
known copolymers can be used on their own as stoveable coating
agents (in the reference cited column 1, lines 56-61). The
combination of these copolymers with aminoplast resins (in the
cited reference column 3, lines 52-62) and with phenol-formaldehyde
resins (in the cited reference column 3, lines 63-66) is also
indicated; in addition, it is possible to use epoxypoly-ethers (in
the cited reference column 3, lines 67-75) at the same time. These
coating agents are stoved at 121.degree. to 205.degree. C. for 30
to 120 minutes. However, the use of these copolymers together with
polyisocyanates is not contemplated.
SUMMARY
The subject of the invention is a process for the production, by
shaping while removing the solvent, of coatings composed of
polyhydroxy compounds based on copolymers which contain hydroxyl
groups and which are reaction products from mixtures of
polymerisable vinyl compounds which contain
.alpha.,.beta.-ethylenically unsaturated monocarboxylic or
dicarboxylic acids and styrene, or derivatives thereof, and of
glycidyl esters, as well as polyisocyanates in solvents which do
not contain active hydrogen atoms, characterised in that
A. 60-80% by weight of copolymers which contain hydroxyl groups and
which have a hydroxyl group content of 3.5 to 6.5% by weight and
which have been manufactured, in the presence of mixtures of diacyl
peroxides or peresters and alkyl hydroperoxides or dialkyl
peroxides as polymerisation initiators, from:
(a) 5-24% by weight of glycidyl esters of
.alpha.-alkylalkanemonocarboxylic acids and/or
.alpha.,.beta.-dialkylalkanemonocarboxylic acids of the following
empirical formula C.sub.12-14 H.sub.20-26 O.sub.3 with the slow,
uniform addition of
(b) 12-30% by weight of hydroxyethyl acrylate and/or hydroxyethyl
methacrylate,
(c) 1-10% by weight of acrylic acid,
(d.sub.1) 20-50% by weight of styrene and
(d.sub.2) 5-35% by weight of methyl methacrylate,
the components a, b, c, d.sub.1 and d.sub.2 having been employed in
such quantities that their total adds up to 100% by weight and the
polymerisation and condensation reactions taking place
simultaneously and jointly and the additional condition applying
that the components a, b and c have been employed in such
quantities that the copolymers have a hydroxyl group content of 3.5
to 6.5% by weight, and
B. 20-40% by weight of an organic polyisocyanate, it being
necessary that (A) and (B) together give numerical values of 100%
by weight, are employed.
A further embodiment of the preceding process is characterised in
that
A. 63-68% by weight of the copolymers which contain hydroxyl groups
and
B. 32-37% by weight of an organic triisocyanate which has been
obtained by reacting 3 mols of hexamethylene diisocyanate and 1 mol
of water,
it being necessary that (A) and (B) together give numerical values
of 100% by weight, are employed.
A further embodiment of the process of this invention is
characterised in that 1-10% by weight of reactive melamine resins,
relative to the weight of the binder component, are used at the
same time as a further binder.
An embodiment which is specially preferred in characterised in that
the component (A) is employed in the form of a solution containing
10-30% by weight of inert organic solvents which are customary in
the lacquer industry and 70-90% by weight of copolymers, it being
necessary that the % by weight add up to 100%.
An embodiment of the process of the invention which is specially
preferred is characterised in that the component (A) which is
employed consists of a copolymer which has a hydroxyl group content
of 4.5.+-.0.3% by weight and which has been obtained from a mixture
consisting of
(A") 20-25% by weight of ethylglycol acetate and
(B") 75-80% by weight of a reaction mixture of the components a to
d.sub.2, the component to be esterified, that is to say
(a) 11-12% by weight of glycidyl esters of
.alpha.,.alpha.-dialkylalkanemonocarboxylic acids of the following
empirical formula C.sub.13 H.sub.24 O.sub.3.sup.(+) which have been
obtained by reacting tripropylene carbon monoxide and water and
which consist almost exclusively of monocarboxylic acids with
highly branched C.sub.10 chains, being heated with the ethylglycol
acetate to 165.degree. to 170.degree. C. and a mixture consisting
of
(b) 25-26% by weight of hydroxyethyl acrylate and/or hydroxyethyl
methacrylate,
(c) 3-4% by weight of acrylic acid,
(d.sub.1) 44-48% by weight of styrene,
(d.sub.2) 10-16% by weight of methyl methacrylate,
(e) 2-2.5% by weight of tert.-butyl perbenzoate and
(e') 1-1.5% by weight of cumene hydroperoxide,
dissolved to form an 80% strength solution in a mixture of
alcohols, ketones and cumene, it being necessary that the sum of
the monomers a to d.sub.2 adds up to 100% by weight, having been
added slowly and uniformly in the course of 6 to 10 hours and the
temperature having been kept at 170.degree..+-.5.degree. C. in the
course thereof until the solids content of the solution has reached
a value of 80.+-.1% by weight, the polymerisation and condensation
reactions having taken place jointly and simultaneously and the
copolymers having a hydroxyl group content of 4.5.+-.0.3.
The manufacture of the copolymers and copolymer solutions employed
in the process has been described in greater detail in the German
patent application of the same date entitled "Copolymer solution
composed of acrylic resin, process for its manufacture and the use
thereof in reactive lacquers".
It is also possible to use the copolymers (A') in repair lacquers
in coating agents which dry physically in air, in quantities of
(A') 20-80% by weight of copolymers containing hydroxyl groups,
manufactured according to the invention, and
(B") 80-20% by weight of thermoplastic copolymers manufactured from
98-99.5% by weight of methyl methacrylate and/or ethyl
methacrylate, and 0.5-2% by weight of methacrylic acid or acrylic
acid,
it being necessary that the components add up to 100% by
weight.
The thermoplastic copolymers (B") are manufactured by dissolving
the monomers in aromatic solvents, such as, for example, benzene,
toluene or xylene, and heating the mixture to a temperature of
60.degree. to 120.degree. C., preferably 80.degree. to 100.degree.
C., and adding the polymerisation initiator, for example dibenzoyl
peroxide or tert.-butyl peroctoate or tert.-butyl perbenzoate,
preferably dissolved in aromatic solvents, to the mixture of
monomers in the course of about 1 to 5 hours, preferably 2 to 4
hours, and carrying out polymerisation at 80.degree. to 100.degree.
C. Polymerisation is carried out here to a solids content of 40 to
55% by weight. The proportion of peroxide is 0.4 to 1% by weight,
relative to the monomer mixtures employed. The thermoplastic
copolymers, which are present dissolved in toluene or mixtures of
xylene and n-butanol as 40% strength by weight solutions, have
viscosities of W-Z.sub.5, measured by the Gardner-Holdt method at
25.degree. C.
The copolymers (A) used according to the invention also produce,
surprisingly, the required good compatibility with thermoplastic
copolymers. The known copolymer solutions, on the other hand,
exhibit no compatibility with thermoplastic copolymers.
The particular advantage of the compatibility of the copolymer
solution (A') used according to the invention with the
thermoplastic copolymers (B") consists in the fact that blemishes
in a finished coat of lacquer after final assembly, for example in
a finished automobile body, can be touched-up, if it is necessary
to overlacquer the coating agent according to the invention which
consists of the copolymers manufactured according to the invention
and polyisocyanates.
When using combinations of binders consisting of 20 to 80% by
weight, preferably 40 to 60% by weight, of copolymer used according
to the invention and 80 to 20% by weight, preferably 60 to 40% by
weight, of a thermoplastic copolymer, tack-free drying is achieved
outstandingly rapidly, within 5 to 10 minutes at approx. 20.degree.
C. After a drying time of a further hour at 20.degree. C.,
surface-hard coats of lacquer are obtained which are resistant to
premium motor fuels.
The organic solvents which are used as the component A" are those
which are customary in the lacquer industry, on their own or as
mixtures, such as, for example, acetone, methyl ethyl ketone,
methyl isobutyl ketone or cyclohexanone, ethyl acetate, butyl
acetate, glycol monomethyl ether-acetate, glycol monoethyl
ether-acetate, glycol monobutyl ether-acetate, acetoacetic acid
methyl ester, acetoacetic acid ethyl ester, acetoacetic acid butyl
ester, benzene, toluene, xylene and/or aromatic solvent mixtures
having a boiling range of 150.degree. to 200.degree. C.
Organic solvents which, on their own or as mixtures, have a boiling
range of 150.degree. to 200.degree. C. are preferred. These
include, for example, ethylglycol acetate, acetoacetic acid methyl
ester, acetoacetic acid ethyl ester and mixtures of aromatic
solvents having a boiling range of 150.degree. to 180.degree. C.
Ethylglycol acetate is particularly suitable for the manufacture of
the copolymers A. It can be removed, partially or wholly, by
distillation and can be replaced by lower-boiling solvents which
have a better solubility for the copolymers used. The following are
particularly suitable for this purpose: acetone, methyl ethyl
ketone, methyl isobutyl ketone, ethyl acetate and butyl
acetate.
5 to 24, preferably 10 to 24, % by weight of glycidyl esters of
.alpha.-alkylalkanemonocarboxylic acids and/or
.alpha.,.alpha.-dialkylalkanemonocarboxylic acids of the following
empirical formula C.sub.12-14 H.sub.20-26 O.sub.3 are used, on
their own or as a mixture, as the component a. The empirical
formula C.sub.3 H.sub.5 O applies to the glycidyl radical in the
glycidyl esters of the .alpha.-alkylalkanemonocarboxylic acids
and/or .alpha.,.alpha.-dialkylalkanemonocarboxylic acids. The
mixture of .alpha.-alkylalkanoic acids and
.alpha.,.alpha.-dialkylalkanoic acids represent monocarboxylic
acids which contain C.sub.9, C.sub.10 and C.sub.11 chains. The
manufacturing processes for the production of the abovementioned
.alpha.-alkylalkanemonocarboxylic acids are based on the pioneering
work of Dr. H. Koch of the Max-Planck-Institute for Coal Research
in Muhlheim, Federal Republic of Germany. The acids are completely
saturated and are very highly substituted on the carbon atom in the
.alpha.-position. Acids having two hydrogen atoms on the
.alpha.-carbon atom are not present and only 6-7% of these acids
contain one hydrogen atom. Cyclic material is present in addition
(Deutsche Farben Zeitschrift Number 10 /Year 16, page 435). It is
preferable to employ .alpha.-alkylalkanemonocarboxylic acids and/or
.alpha.,.alpha.-dialkylalkanemonocarboxylic acids which have been
obtained by reacting tripropylene, carbon monoxide and water and
which consist almost entirely of monocarboxylic acids having highly
branched C.sub.10 chains. The empirical formula of the glycidyl
ester compound is C.sub.13 H.sub.24 O.sub.3.
12 to 30% by weight of hydoxyethyl acrylate and/or hydroxyethyl
methacrylate are employed as the component b. Hydroxyethyl acrylate
imparts high elasticity to the copolymers. This is required
particularly in cases where the metal substrate is shaped by an
impact process. A further outstanding property of hydroxyethyl
acrylate in the copolymers used consists in the fact that it
promotes the wetting of pigments, especially in the case of organic
pigments and carbon black. Hydroxymethyl methacrylate gives the
copolymers used a particularly high film hardness, which is
required, in particular, for the formulation of polyisocyanate
reactive clear lacquers to give two-coat metal effect
lacquering.
18 to 26% by weight of hydroxyethyl acrylate are used particularly
preferentially as the component b, since particularly low
viscosities produce a high solids content in the condition ready
for spraying.
1 to 10% by weight of acrylic acid, preferably 2 to 9% by weight of
acrylic acid, are employed as the component c.
20 to 50% by weight of styrene are employed as the component
d.sub.1 ; this gives second order transition temperatures of about
100.degree. C. as a homopolymer and can thus be regarded as a
so-called hard monomer which imparts the desired film hardness to
the copolymers used.
5 to 35% by weight, preferably 10 to 35% by weight, of methyl
methacrylate are employed as the component d.sub.2. As a
copolymerisation component, methyl methacrylate imparts a
particularly high resistance to weathering, especially in
weathering tests in the Florida climate, to the copolymers
used.
Mixtures of peroxides consisting of at least two peroxides are used
as the polymerisation initiators in the manufacture of the
copolymers used. The mixtures of peroxides have a different
chemical structure.
Peroxides of the first group e are represented by diacyl peroxides,
such as dibenzoyl peroxide, or peresters, such as tert.-butyl
perbenzoate, tert.-butyl peroctoate or tert.-butyl
perisononanate.
Peroxides of the second group e' are represented by alkyl
hydroperoxides, such as tert.-butyl hydroperoxide and cumene
hydroperoxide, or dialkyl peroxides, such as di-tert.-butyl
peroxide or dicumyl peroxide.
In each case, 1 to 3.5% by weight of a peroxide from the first
group e and 1 to 3% by weight of a peroxide from the second group,
relative to 100% by weight of the components a, b, c, d.sub.1 and
d.sub.2, are used as the mixtures of peroxides.
The following combinations of peroxides from the groups one and two
are employed: dibenzoyl peroxide/tert.-butyl hydroperoxide;
dibenzoyl peroxide/cumene hydroperoxide; dibenzoyl peroxide/dicumyl
peroxide; tert.-butyl perbenzoate/butyl hydroperoxide; tert.-butyl
perbenzoate/cumene hydroperoxide; tert.-butyl
perbenzoate/di-tert.-butyl peroxide; tert.-butyl
perbenzoate/dicumyl peroxide; tert.-butyl peroctoate/tert.-butyl
hydroperoxide; tert.-butyl peroctoate/cumene hydroperoxide;
tert.-butyl peroctoate/di-tert.-butyl peroxide; tert.-butyl
peroctoate/dicumyl peroxide; tert.-butyl perisononanate/tert.-butyl
hydroperoxide; tert.-butyl perisononanate/cumyl hydroperoxide;
tert.-butyl perisononanate/di-tert.-butyl peroxide or tert.-butyl
perisononanate/dicumyl peroxide.
The preferred embodiment includes the following combinations of
peroxides: dibenzoyl peroxide/cumene hydroperoxide; dibenzoyl
peroxide/di-tert.-butyl peroxide; tert.-peroctoate/cumene
hydroperoxide; tert.-butyl peroctoate/di-tert.-butyl peroxide;
tert.-butyl perbenzoate/cumene hydroperoxide and tert.-butyl
perbenzoate/di-tert.-butyl peroxide.
Mixtures of peroxides which contain, as the component e, 1.5 to
2.5% by weight of tert.-butyl perbenzoate and, as e', 1 to 2.5% by
weight of cumene hydroperoxide, dissolved to form an 80% strength
solution in a mixture of alcohols, ketones and cumene, relative to
100% by weight of the components a, b, c, d.sub.1 and d.sub.2, are
the most preferred embodiment. It is found, surprisingly, that, in
the most preferred embodiment of the peroxide mixtures and in the
most preferred embodiment of the copolymer solution, 75 to 85%
strength by weight copolymer solutions in ethylglycol acetate are
obtained, which, as a 70% strength by weight solution in
ethylglycol acetate, give a viscosity of X-Z.sub.3 by the
Gardner-Holdt method at 25.degree. C. and, when an 80% strength by
weight solution in ethylglycol acetate is diluted with xylene to 25
seconds, measured at 25.degree. C. in a DIN cup having a 4 mm flow
orifice, give a solids content of 45 to 65% by weight.
The mixtures of peroxides are generally dissolved in the monomers
or are added separately to the polymerisation medium, solvent or
solvent mixtures. In some cases, small proportions of the mixtures
of peroxides, up to 20% by weight of the quantity of peroxides
employed, can also be dissolved in the solvent or solvent mixtures
and the remaining quantity of the peroxide mixtures is added
uniformly to the polymerisation medium, solvent or solvent mixture,
separately from the monomers or dissolved in them.
It proves particularly suitable to dissolve the tert.-butyl
perbenzoate of the peroxide mixtures in the monomers and to add the
mixtures which are produced, uniformly within a time of 6 to 10
hours, to the polymerisation and condensation medium, which
consists of the solvent or solvent mixture and glycidyl esters of
.alpha.-alkyalkanemonocarboxylic acids and/or
.alpha.,.alpha.-dialkylalkanemonocarboxylic acids.
As a result of this the optimum lowering of viscosity is achieved,
which gives the copolymers which are used. The reaction of acrylic
acid with the glycidyl esters of the
.alpha.,.alpha.-dialkylalkanemonocarboxylic acids proceeds
approximately according to the following formula: ##STR4##
The reaction between the carboxyl group and the glycidyl group is
carried out under the conditions of 0.95 to 1.1 mols of acrylic
acid per mol of glycidyl ester of
.alpha.,.alpha.-dialkylalkanemonocarboxylic acids of the following
empirical formula C.sub.12-14 H.sub.20-26 O.sub.3, having an
epoxide equivalent of 240-250.
The acid number of the copolymers is 5 to 12 and is provided by
excess acrylic acid and by the organic acids formed as a scission
product in the decomposition of the peroxide, and is to be regarded
as external acid.
The hydroxyl group content of the copolymers is 3.5 to 6.5,
preferably 4 to 5.5, % by weight.
The content of hydroxyl groups in the copolymers is calculated by
means of the following formula: ##EQU1##
Thus, the reaction product from 1 mol of acrylic acid, which
corresponds to 72 g of acrylic acid, and 1 mol of glycidyl ester of
.alpha.,.alpha.-dialkylalkanemonocarboxylic acids of the following
empirical formula C.sub.12-14 H.sub.20-26 O.sub.3 which has an
average epoxide equivalent of 245, which corresponds to 245 g of
glycidyl ester, gives a molecular weight of 317.
Under the conditions of an equivalent conversion, there are, for 10
g of the abovementioned glycidyl ester, 2.94 g of acrylic acid,
which corresponds to a sample weight of 12.94 g of the compound
containing hydroxyl groups.
The following numerical expression is then applicable to the
formula set out above: ##EQU2##
The other compounds containing hydroxyl groups have the following
molecular weights: hydroxyethyl acrylate, molecular weight 116 and
hydroxyethyl methacrylate, molecular weight 130. For 26% by weight
of hydroxyethyl acrylate, the following OH percentages result from
the following numerical expression: ##EQU3##
The sum of both compounds which contain hydroxyl groups, the
reaction product of glycidyl ester and acrylic acid and the
hydroxyethyl acrylate, gives a hydroxyl group content of 4.5% of
OH.
If the conditions that the components a, b and c are employed in
such quantities that the copolymers have a hydroxyl group content
of 3.5 to 6.5% by weight, preferably 4 to 5.5% by weight, are
maintained, the components a and b should be adjusted to the
component c in such a way that the desired hydroxyl group content
is achieved.
This means that, if smaller percentages by weight of the components
a and b are employed, higher percentages by weight of the component
c must be taken in order to manufacture the copolymers which are
used. If larger percentages by weight of the components (a) and (b)
are employed, smaller percentages by weight of the component (c)
must be taken in order to manufacture the copolymers (A) which are
used.
The starting point in this approach must always be that the
copolymers which are used should produce as high a solids content
as possible and the relevant test viscosity is that obtained on
diluting the copolymer solutions with xylene to a flow viscosity of
25 seconds at 25.degree. C., measured in a DIN cup having a 4 mm
flow orifice.
The copolymers (A) which are used are manufactured by heating the
solvents or solvent mixtures, which preferably have a boiling range
of 150.degree. to 180.degree. C., to 165.degree. to 180.degree. C.
in a reaction flask as a mixture with the glycidyl esters of
.alpha.-alkylalkanemonocarboxylic acids and/or
.alpha.,.alpha.-dialkylalkanemonocarboxylic acids, dissolved in the
solvent. The mixtures of monomers a, b, c, d.sub.1 and d.sub.2 and
the peroxide mixtures e and e' are added slowly and uniformly over
a period of time of 6 to 10 hours, separately, or preferably
jointly, to this heated mixture in the reaction flask, the
polymerisation temperature not being allowed to fall below
165.degree. C. After the addition of monomer and peroxide,
polymerisation is carried out at reflux temperature for a further 2
to 3 hours until the solids content of the solution has reached the
theoretical value of between 70 and 90% by weight. The copolymers
used must have the predetermined test viscosity of X to Z.sub.4,
measured by the Gardner-Holdt method, for 70% strength by weight
copolymer solutions in ethylglycol acetate. The copolymers are
manufactured under the proviso that the polymerisation and
condensation reactions take place simultaneously and jointly at
165.degree. to 180.degree. C.
The copolymers A are used as the component A in reactive lacquers
together with a polyisocyanate component B.
The following polyisocyanates, for example, can be employed as the
component B: ethylene diisocyanate, propylene diisocyanate,
tetramethylene diisocyanate, hexamethylene diisocyanate,
1,3-dimethylbenzene diisocyanate, 1,4-dimethylcyclohexane
diisocyanate, 1-methylcyclohexane 2,4-diisocyanate,
4,4'-methylene-bis(cyclohexyl diisocyanate), phenylene
diisocyanate, 2,4-toluylene diisocyanate, naphthylene diisocyanate,
3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, lysine
diisocyanate, triphenylmethane triisocyanate, trimethylbenzene
2,4,6-triisocyanate, 1-methylbenzene 2,4,6-triisocyanate and
diphenyl 2,4,4'-triisocyanate; diisocyanates or triisocyanates
which have been manufactured by reacting a polyisocyanate with a
low-molecular diol or triol (for example ethylene glycol, propylene
glycol, 1,3-butylene glycol, neopentyl glycol,
2,2,4-trimethyl-1,3-pentanediol, hexanediol, trimethylolpropane or
trimethylolethane); and cyanurates which have been obtained by
reacting the said diisocyanates in a cyclisation reaction. A
particularly valuable polyisocyanate is the triisocyanate which
contains biuret groups and which is obtained by reacting 3 mols of
hexamethylene diisocyanate and one mol of water.
Instead of the polyisocyanates, it is also possible to use
compounds which split off polyisocyanates and also reaction
products, containing isocyanate groups, of polyhydric alcohols and
polyisocyanates, for example the reaction product of 1 mol of
trimethylolpropane and 3 mols of toluylene diisocyanate, and also
trimerised or polymerised isocyanates, such as are described, say,
in German Patent Specification 951,168.
In addition, a reaction product of 1 mol of water and 3 mols of
hexamethylene diisocyanate having an NCO content of 16-17% by
weight is also possible. The last-mentioned reaction product of
water and hexamethylene diisocyanate is particularly preferred. The
NCO content of the reaction product is applicable to a 75% strength
solution in xylene/ethylglycol acetate.
When used in reactive lacquers, the reaction of the copolymers A
which contain hydroxyl groups with the organic polyisocyanates B
can, moreover, be carried out with 0.5 to 1.3 NCO groups per
hydroxyl group, depending on the end use of the reaction products.
It is preferable to carry out the reaction in such a way that the
quantities of the organic polyisocyanate, relative to the total
hydroxyl content of the components present in the reaction mixture,
are present in an amount of 0.7 to 1.0 isocyanate group per
hydroxyl group.
In order to use the copolymers, the mixtures of copolymers A which
contain hydroxyl groups and which contain solvent, and
polyisocyanate B are applied to the appropriate substrates in the
simplest imaginable manner, say after adding known auxiliaries,
such as levelling agents and pigments or dyestuffs, by spraying,
dipping, pouring, brushing or other suitable measures, and the
sheet-like structures are dried at room temperature; in special
cases, say when using compounds which split off isocyanates, it is
possible to stove the coatings, which depends essentially on the
substrates used and on the requirements for the coatings set by
practical use.
The copolymers used in the process can be employed together with
polyisocyanates, in the reactive lacquers already illustrated, for
the production of coatings or coverings on substrates of the most
diverse kind, for example porous or non-porous substrates, such as
textile non-wovens, leather or plastics. The production of coatings
on wood or metals is singled out particularly. In every case,
high-gloss, pore-free, elastic coatings which have a very hard
surface and are resistant to solvents are obtained, which can be
treated both with strong inorganic acids and with strong alkali
metal hydroxide solutions, without the coatings being attacked even
to the slightest extent. Coatings of this type display, in
addition, an outstanding resistance to weathering and resistance to
yellowing.
In pigmented coating compositions based on the polyisocyanate
reactive lacquer binder solutions according to the invention, the
total solids content in the coating composition is between 62 and
90% by weight, preferably between 67 and 90% by weight. The ratio
of pigment to binder can be between 1:20 and 2:1. The following can
be added as pigments: inorganic pigments, such as chrome yellow,
Prussian blue, Brunswick green and titanium pigments, for example
titanium dioxide, extended titanium pigments (which have been
extended either with precipitated or natural extenders, such as
alkaline earth metal sulphates, for example calcium sulphate and
barium sulphate), tinted titanium pigments and titanates, such as
barium, tin, lead and magnesium titanates. Other types of inorganic
pigments can also be used, for example zinc sulphide pigments, such
as zinc sulphide, lithopone, extended zinc sulphide pigments, such
as lithopone on a calcium compound substrate, or zinc sulphide
extended with natural extenders, zinc oxide or antimony oxide, or
organic pigments, that is to say organic dyestuffs which are free
from sulphonic acid groups, carboxylic acid groups or other groups
which impart solubility in water. Pigments also include,
conceptually, other organic dyestuffs which are insoluble in water,
for example calcium or barium lakes of azo dyestuffs.
The constituents for the stoving lacquers to be used can be
processed to give lacquers by customary processes, preferably as
follows. The pigment and a suitable quantity of solvent are mixed
with part of the copolymers according to the invention to give a
pasty or solid pigment taste. After the mixture has been well
dispersed in a stirred ball mill, the residual copolymer and other
additives are combined with the resulting paste or dispersion and
the mixture is then formulated with the solvents, preferably
xylene, butyl acetate and/or ethylglycol acetate or acetone, to
give a viscosity at which it can be sprayed and a solids content of
62 to 90% by weight, preferably between 67 and 90% by weight, of
non-voltatile substances.
Preparation of the Copolymer 1 (A) which contains Hydroxyl
Groups
(A) 28 g of ethylglycol acetate (=21.9% by weight) and
(B) 100 g of component B (=78.1% by weight) are reacted as follows:
Component A) plus
(a) 11.7 g of glycidyl esters of
.alpha.,.alpha.-dialkylalkanemonocarboxylic acids of the following
empirical formula C.sub.13 H.sub.24 O.sub.3 having an epoxide
equivalent of 240-250, designated only as glycidyl esters of
.alpha.,.alpha.-dialkylmonocarboxylic acids in the following text,
are heated to 167.degree. C. in a flask equipped with a stirrer,
reflux condenser and water separator, as well as a thermometer, and
a mixture (component B of hydroxy copolymer) consisting of:
(b) 25.5 g of hydroxyethyl acrylate,
(c) 3.3 g of acrylic acid,
(d.sub.1) 46.2 g of styrene and
(d.sub.2) 13.3 g of methyl methacrylate, it being necessary for the
% by weight of the components a, b, c, d.sub.1 and d.sub.2 to add
up to 100% by weight, and
(e) 2.7 g of tert.-butyl perbenzoate =2% by weight and
(e') 2.0 g of 80% strength cumene hydroperoxide=1.2% by weight,
the % by weight figures relating to the total mixture of the
components A and B, is added uniformly, at a temperature which
rises to 170.degree. C., in the course of 7 hours, while the
mixture boils and the reflux is cooled. When the addition is
complete, polymerisation is continued for a further 2 hours until a
solids content of 81.0% by weight has been reached.
This copolymer illustrates the most preferred embodiment of the
invention for the manufacture of lacquers.
The acid number of the solid component is 7.5. The viscosity of a
70% strength by weight solution in ethylglycol acetate is Z.sub.2
to Z.sub.3 by the Gardner-Holdt method. When the viscosity is
adjusted with xylene to 25 seconds at 25.degree. C., measured in a
DIN cup having a 4 mm flow orifice, the solids content is 47% by
weight. The copolymer has a hydroxyl group content of 4.5% by
weight.
Comparison test according to the state of the art
Comparison Test 1 (taking into account the Example in French Patent
Specification 1,556,309, which is the nearest approach to the
invention).
The hydroxyl group content, relative to the copolymers, in the
Examples 1 to 10 in French Pat. No. 1,556,309 is:
in Example 1=0.8% of hydroxyl groups
in Example 2=1% of hydroxyl groups
in Example 3=1.26% of hydroxyl groups
in Example 4=1.52% of hydroxyl groups
in Example 5=1.41% of hydroxyl groups
in Example 6=1.41% of hydroxyl groups
in Example 7=1.66% of hydroxyl groups
in Example 8=1.85% of hydroxyl groups in Example 9=1.85% of
hydroxyl groups
in Example 10=3.18% of hydroxyl groups
The nearest approach to the invention is Example 10 in French
Patent Specification 1,556,309, which has a hydroxyl group content
of 3.18%.
The procedure described in Example 10 of French Patent
Specification 1,556,309 is followed.
10 parts by weight of 2-hydroxyethyl methacrylate,
30 parts by weight of methyl methacrylate,
25 parts by weight of styrene,
15 parts by weight of ethyl acrylate,
20 parts by weight of a reaction product obtained in accordance
with reaction (a),
1.3 parts by weight of lauryl-mercaptan,
1.5 parts by weight of azobisisobutyronitrile,
20 parts by weight of butyl acetate,
20 parts by weight of ethyl acetate,
30 parts by weight of toluene,
10 parts by weight of ethylglycol acetate and
20 parts by weight of xylene
were converted into a solution of copolymers. The viscosity of the
50% strength by weight solution is R by the Gardner-Holdt
method.
The copolymer solution has a considerable sediment and is also
turbid. The constituents which have precipitated in a solid form
could be removed by filtration. The turbidity of the resin solution
could not be eliminated. When the viscosity is adjusted with xylene
to 25 seconds at 25.degree. C., measured in a DIN cup having a 4 mm
flow orifice, the solids content is 37% by weight. The copolymer
has a hydroxyl group content of 3.18% by weight.
Comparison test taking into account the state of the art and the
inventive concept of the present invention
Comparison Test 2
The procedure described in Comparison Test 1 is followed, the
monomers alone having been adapted to the copolymer 1 (A) which was
used. The following were used:
25.5% by weight of hydroxyethyl acrylate,
13.3% by weight of methyl methacrylate,
46.2% by weight of styrene and
15% by weight of a reaction product obtained in accordance with
reaction (a) of French Patent Specification 1,556,309. The
copolymer solution displayed a particularly strong, milky turbidity
which could not be removed by filtration. The copolymer has a
hydroxyl group content of 4.5% by weight. The viscosity of a 50%
strength by weight solution was Z, measured by the Gardner-Holdt
method at 20.degree. C. When the viscosity was adjusted with xylene
to 25 seconds at 25.degree. C., measured in a DIN cup having a 4 mm
flow orifice, the solids content was 28% by weight.
Comparison Test 3
The procedure described for copolymer 1 (A) was followed, but, in
divergence, polymerisation was carried out at a temperature of
160.degree. C. using tert.-butyl perbenzoate alone. The viscosity
of a 70% strength by weight solution is ethylglycol acetate,
measured by the Gardner-Holdt method, is higher than Z.sub.6. The
resin solution exhibits a turbidity which could not be removed by
filtration. When the viscosity was adjusted with xylene to 25
seconds at 25.degree. C., measured in a DIN cup having a 4 mm flow
orifice, the solids content was 38% by weight.
Comparison Test 4
The procedure described for copolymer 1 (A) was followed, but, in
divergence, polymerisation was carried out at a temperature of
160.degree. C. using cumene hydroperoxide alone, as an 80% strength
solution in a mixture of alcohols, ketones and cumene. The
viscosity of a 70% strength by weight solution in ethylglycol
acetate, measured by the Gardner-Holdt method, is higher than
Z.sub.6. The resin solution exhibits a strong turbidity which
cannot be removed by filtration. When the viscosity was adjusted
with xylene to 25 seconds at 25.degree. C., measured in a DIN cup
having a 4 mm flow orifice, the solids content was 34% by
weight.
Preparation of the copolymer 2 (A) which contains hydroxyl
Groups
A 28 g of ethylglycol acetate=21.9% by weight and B 100 g of
component B=78.1% by weight are reacted as follows:
Component A and
(a) 24 g of glycidyl esters, as described in Example 1, are heated
to 172.degree. C. in a flask equipped with a stirrer, a reflux
condenser and a water separator and a thermometer and a mixture
consisting of
(b) 19.1 g of hydroxyethyl methacrylate,
(c) 7.2 g of acrylic acid,
(d.sub.1) 28.1 g of styrene and
(d.sub.2) 21.6 g of methyl methacrylate, it being necessary for the
% by weight of the components a, b, c, d.sub.1 and d.sub.2 to add
up to 100% by weight, and
(e) 2.7 g of tert.-butyl perbenzoate=2% by weight and
(e') 2.0 g of 80% strength cumene hydroperoxide=1.2% by weight,
the percentage by weight figures relating to the total weight of
the components (A) and (B), is added uniformly in the course of 7
hours while the mixture boils and the reflux is simultaneously
cooled. When the addition is complete, polymerisation is continued
for a further 2 hours until a solids content of 80% by weight has
been reached. The acid number of the solid component is 11. The
viscosity of a 70% strength by weight solution in ethylglycol
acetate is Y-Z, measured by the Gardner-Holdt method. When the
viscosity is adjusted with xylene to 25 seconds at 25.degree. C.,
measured in a DIN cup having a 4 mm flow orifice, the solids
content is 52% by weight. The copolymer has a hydroxyl group
content of 4.17% by weight. The copolymer solution contains no
insoluble solid components and is free from turbidity.
Preparation of the thermoplastic copolymer 1
600 g of toluene,
200 g of ethyl methacrylate,
4 g of acrylic acid and
296 g of methyl methacrylate are heated to reflux temperature in a
flask equipped with a stirrer and a reflux condenser and a water
separator and the following mixture, consisting of: 150 g of
toluene and
3.5 g of dibenzoyl peroxide, as a 75% strength suspension in
water,
is added uniformly in the course of 2 hours. After a polymerisation
time of 2 hours, a further 2 g of dibenzoyl peroxide, as a 75%
strength suspension in water, are added and polymerisation is
continued under reflux. The solids content of the solution is 40%
by weight. The viscosity of the solution exhibits a value of X-Y,
measured by the Gardner-Holdt method at 25.degree. C. The acid
number is 5.
Preparation of the thermoplastic copolymer 2
300 g of xylene,
1.5 g of methacrylic acid and
300 g of methyl methacrylate are heated to 85.degree. C. in a flask
equipped with a stirrer and a reflux condenser and a water
separator and the following mixture, consisting of:
50 g of xylene and
2.5 g of dibenzoyl peroxide, as a 75% strength suspension in
water,
is added uniformly in the course of 3 hours. After polymerising for
2 hours at a constant temperature, a further g of dibenzoyl
peroxide, as a 75% strength suspension in water, is added and
polymerisation is continued for a further 2 hours until the
theoretical solids content of 46% by weight has been reached. When
diluted with n-butanol to 40% by weight, the solution has a
viscosity of Z.sub.3 -Z.sub.4, measured by the Gardner-Holdt method
at 25.degree. C. The acid number of the polymer is 4.
EXAMPLE 1
Reactive lacquer based on 70 percent by weight of copolymer 1 (A)
and 30 percent by weight of an organic triisocyanate, relative to
the solids content.
61.6 g of a solution of copolymer 1 in ethylglycol acetate
(copolymer 1 (A), dissolved solids 81% by weight) are dissolved in
a 1:1 mixture of xylene and ethylglycol acetate, together with 28.6
g of a 75% strength by weight solution of a triisocyanate which has
a NCO content of 16.5 to 17.0% by weight and which has been
obtained by reacting 3 mols of hexamethylene diisocyanate and 1 mol
of water. 0.5 g of diethylethanolamine are added and thoroughly
mixed and xylene is added to adjust the mixture to spraying
viscosity, namely 25 seconds at 25.degree. C., measured in a DIN
cup having a 4 mm flow orifice. The lacquer was applied to glass
plates at a wet film layer thickness of 90 .mu.m and was dried in
air at 18.degree. to 20.degree. C. The pendulum hardness, measured
by Konig's method (DIN 53,157) is 60 seconds after one day, 140
seconds after three days and 180 seconds after seven days. When
stoved for 30 minutes at 80.degree. C., the films gave pendulum
hardnesses of 102 seconds, rising to 180 seconds after being stored
for one day at room temperature and to 202 seconds after 3 days.
After stoving for 30 minutes at 120.degree. C., the films gave
pendulum hardnesses of 203 seconds which did not alter further on
storage. The cured films were particularly insensitive towards the
fingernail test and were very resistant to xylene and acetone.
After weathering for 18 months in the Florida climate, a top coat
of lacquer (pigmented with 0.6 part by weight of rutile:1 part by
weight of binder combination) applied to steel sheets which had
been primed and zinc phosphated, gave a loss of gloss of only 10%
compared with the gloss measured before weathering.
Black lacquers with a particularly high gloss are obtained if 20
parts by weight of FW 200 carbon black together with 270 parts by
weight of the copolymer 1 solution, calcium naphthenate and
silicone oil, as a 1% strength solution in xylene, are subjected,
using an appropriate quantity of xylene and butyl acetate, to a
grinding process lasting about 30 to 40 minutes, using a
"sandmill". After adding a further 270 parts by weight of copolymer
1 solution and adjusting the viscosity with xylene/ethylgylcol
acetate in the ratio of 1:1 to 25 seconds in a DIN cup having a 4
mm flow orifice, lacquers are obtained which are stable against
flocculation for several months.
A reactive lacquer is prepared based on 70% by weight of copolymer
and 30% by weight of an organic triisocyanate which has been
obtained by reacting 3 mols of hexamethylene diisocyanate and 1 mol
of water. The coatings produced therewith, which are stoved for 30
minutes at 80.degree. C., give films having an insensitive surface,
so that in motor vehicle repair lacquering the adhesive masking
tapes can be removed before a completely cooled condition is
reached, and assembly can be carried out. The "pot-life" of the
clear lacquer combination of copolymer 1/ethylglycol acetate
solution, which has been adjusted with xylene to a viscosity of 25
seconds, and the triisocyanate is such that, after storage at
23.degree. C. for 8 hours, the viscosity is 40 seconds, measured in
a DIN cup having a 4 mm flow orifice at 25.degree. C. This shows
that the binder combination can be processed over a working day of
at least 8 hours, since a doubling of viscosity to 50 seconds is
tolerated by the lacquer processor.
EXAMPLE 2
Reactive lacquer based on 70 percent by weight of copolymer 2 (A)
and 30 percent by weight of an organic triisocyanate, both relative
to the weight of solids.
62.5 g of copolymer 2/ethylglycol acetate solution (copolymer 2
(A), dissolved solids 80% by weight) are dissolved in a 1:1 mixture
of xylene and ethylglycol acetate, together with 28.6 g of a 75%
strength by weight solution of a triisocyanate which has a NCO
content of 16.5-17.0% by weight and which has been obtained by
reacting 3 mols of hexamethylene diisocyanate and 1 mol of water,
and 0.5 g of diethylethanolamine are mixed in and the product is
adjusted with xylene to a spraying viscosity of 25 seconds at
25.degree. C., measured in a DIN cup having a 4 mm flow orifice,
and is applied to glass plates at a wet film layer thickness of 90
.mu.m and dried in air at 18.degree. to 20.degree. C. The pendulum
hardness, measured by Konig's method (DIN 53,157) is 45 seconds
after one day, 110 seconds after three days and 160 seconds after
seven days. After stoving for 30 minutes at 80.degree. C., the
films gave pendulum hardnesses of 75 seconds, rising to 130 seconds
after one day after storage at 23.degree. C. and to 162 seconds
after four days. After stoving for 30 minutes at 120.degree. C.,
the films gave pendulum hardnesses of 165 seconds which did not
alter further on storage. The cured films were particularly
insensitive towards premium motor fuels and xylene.
After weathering for 16 months in the Florida climate, a top coat
of lacquer (pigmented with 0.65 part by weight of rutile:1 part by
weight of binder combination) applied to steel sheets which had
been primed and zinc phosphated, gave a loss of gloss of only 12%
compared with the gloss measured before weathering.
Further comparison tests to demonstrate the technical progress
achieved
Assessment of the appearance of the copolymer solutions
The resin solutions are assessed in respect of flocculation of
solid, insoluble constituents and in respect of turbidity of the
resin solutions. As tests have shown, the solid, insoluble
constituents can be filtered off. Turbidity of the resin solutions
is not removed by filtration (see Table 1).
1=clear solution (highest value) 5=very strong milky turbidity
(lowest value)
0=no flocculation
+=flocculation of solid constituents
As the results in Table 1 show, the copolymer solution used
according to the invention is markedly superior to the known
copolymer solutions.
Preparation of black top lacquers and assessment of the gloss of
the films
A lacquer is prepared from the following components:
270 g of copolymer solution 1 (A) used according to the
invention,
20 g of carbon black, as described in the Company Publication FW
200 of Messrs. Degussa,
4 g of diethylethanolamine,
10 g of silicone oil, as described in the Company Publication
Silikonol L 050 of Bayer, dissolved to form a 1% strength solution
in xylene,
10 g of calcium naphthenate, a liquid having a content of 4% of
calcium,
65 g of butyl acetate and
70 g of xylene,
with the aid of a sand mill, grinding for about 60 minutes. After
adding a further 270 g of copolymer solution 1 (A) used according
to the invention and diluting with a solvent mixture consisting of
equal parts by weight of xylene and butyl acetate to a flow
viscosity of 23 seconds at 20.degree. C., measured in a DIN cup
having a 4 mm flow orifice, the lacquer is poured onto vertical
glass plates and the degree of gloss is tested after the solvent
has evaporated. High-gloss films are obtained which exhibit no
deposition of pigment in the range between 1 and 10 .mu.m. The
weight ratio of binder to pigment is 95.6% by weight of binder to
4.4% by weight of pigment.
Pigmentation and run-off are carried out for the copolymers in the
Comparison Tests 1, 2, 3 and 4 in the same manner and the gloss and
the deposition of pigment of the lacquers are assessed. As the
results in Table 1 show, the copolymer solution used according to
the invention is superior to the known copolymer solutions.
1=high-gloss films with no deposition of pigment (highest
value)
5=matt films and very high deposition of pigment (lowest
value).
Testing the compatibility of the copolymer solutions 1 (A) and 2
(A) used (from Comparison Tests 1 and 2) with the thermoplastic
copolymers 1 and 2
62 parts by weight of copolymer solution 1 (A), consisting of 50
parts by weight of copolymer and 12 parts by weight of ethyglycol
acetate are mixed with 125 parts by weight of thermoplastic
copolymer solution 1, consisting of 50 parts by weight of a
thermoplastic copolymer and 75 parts by weight of toluene, and the
mixture is diluted to a solids content of 40% by weight using a
solvent mixture consisting of xylene and butyl acetate in a 1:1
weight ratio, and is applied to glass plates, and a dry film layer
thickness of 200 to 300 .mu.m was achieved.
After drying at room temperature, the appearance and the
compatibility of the films were investigated. This mixture consists
of 50% by weight of copolymer 1 (A) and 50% by weight of the
thermoplastic copolymer 1.
The copolymer solutions 1 (A) and 2 (A), used according to the
invention, and the copolymers from Comparison Tests 1 and 2 were
mixed with the thermoplastic copolymers 1 and 2 in the manner
described above and the mixtures were applied to glass plates and
the resulting films were assessed. As the results in Table 2 show,
the copolymer solutions used according to the invention are
markedly superior to the known copolymer solutions.
Test for film appearance:
1=high gloss (highest value)
5=very cloudy film (lowest value)
Testing the "pot life" of reactive lacquers
86.6 g of the copolymer solution 1 (A) which is used and 40 g of a
70% strength by weight solution of a triisocyanate which contains
biuret groups and has a NCO content of 16.5 to 17.0% by weight and
has been obtained by reacting three mols of hexamethylene
diisocyanate and one mol of water, are mixed and diluted with
xylene to a flow viscosity of 25 seconds at 25.degree. C., measured
in a DIN cup having a 4 mm flow orifice, and the rise in viscosity
after storage at 23.degree. C. for 6 hours is determined.
The mixing ratio is 70% by weight of the copolymer 1 (A) used
according to the invention and 30% by weight of the triisocyanate
containing biuret groups.
A comparison combination is composed of 70% by weight of the
copolymer from Comparison Test 2 and 30% by weight of the
triisocyanate containing biuret groups.
A further comparison combination is composed of 77% by weight of
copolymer from Comparison Test 1 and 23% by weight of the
triisocyanate containing biuret groups, as described in French Pat.
Specification No. 1,556,309.
The adjustment of viscosity is carried out in the same way using
the solvent mixture described above. As the results in Table 3
show, the reactive lacquers according to the invention are markedly
superior to the known reactive lacquers, since they have a longer
processing life.
Preparation of pigmented two-component reactive lacquers and
testing the run-off tendency of stoved films
The ratio in the combination is 65% by weight of copolymer used
according to the invention and 35% by weight of triisocyanate
containing biuret groups. The proportion by weight of pigment:
binder is 42%:58% by weight.
A lacquer paste is prepared from the following components:
80 g of copolymer solution 1 (A) used according to the
invention,
73 g of titanium dioxide (rutile),
0.5 g of diethylethanolamine,
2.5 g of silicone oil, as described in the Company Publication
Silikonol L 050 of Bayer, dissolved to form a 1% strength solution
in xylene,
2 g of calcium naphthenate, a liquid having a content of 4% of
calcium,
4.5 g of Bentone-38 paste, dissolved to form a 10% strength by
weight solution in xylene/methyl isobutyl ketone in the proportions
86:4 by weight, as described in the
Company Publication of Messrs. Kronos Titan, and a solvent mixture
of xylene and ethylglycol acetate in the proportions 1:1 by weight,
by grinding for 24 hours in a ball mill. To this are added 46.6 g
of a 75% strength by weight solution, dissolved in a mixture of
xylene and ethylglycol acetate, of a triisocyanate which contains
biuret groups and has a NCO content of 16.5 to 17.0% by weight and
which has been obtained by reacting 3 mols of hexamethylene
diisocyanate and one mol of water. This mixture is then diluted
with a mixture of xylene, butyl acetate and ethylglycol acetate in
the proportions 1:1:1 by weight, to a flow viscosity of 22 seconds
at 23.degree. C., measured in a DIN cup having a 4 mm flow
orifice.
This reactive lacquer is applied by the spray application process
to vertical steel sheets so that dry film layer thicknesses of 80
.mu.m are obtained. The time of exposure to air between individual
spray applications should be 30 seconds to one minute at most.
After the spray application is completed, the lacquer film is
exposed to air for approx. 5 minutes and stoved for 30 minutes at
120.degree. C.
1. Comparison test of run-off tendency
The ratio in the combination is 77% by weight of copolymer from
Comparison Test 1 and 23% by weight of triisocyanate containing
biuret groups. The proportion by weight of pigment: binder is 42%
by weight:58% by weight.
2. Comparison test of run-off tendency
The ratio in the combination is 65% by weight of copolymer from
Comparison Test 2 and 35% by weight of triisocyanate containing
biuret groups. The proportion by weight of pigment: binder is 42%
by weight:58% by weight.
In the above Comparison Tests 1 and 2, the pigmentation and the
spray application onto vertical steel sheets are carried out in the
same manner as described above for the copolymer 1 (A) used
according to the invention. The films are stoved for 30 minutes at
120.degree. C.
As can be seen from Table 3, the reactive lacquers used according
to the invention are markedly superior to the known reaction
lacquers by having a lower run-off tendency.
Further comparison tests using reactive lacquers based on the
copolymer solutions used and polyisocyanates in comparison with the
known reactive lacquers of French Patent Specification
1,556,309
A reactive lacquer consisting of 70% by weight of copolymer, which
corresponds to 86.6 g of the copolymer 1 (A) solution used
according to the invention, and 30% by weight of triisocyanate,
which corresponds to 40 g of a 75% strength by weight solution of a
triisocyanate which is dissolved in a mixture of xylene and
ethylglycol acetate and which has been prepared from 3 mols of
hexamethylene diisocyanate and one mol of water and has an NCO
content of 16.5 to 17.0% by weight, is diluted with acetone to a
flow viscosity of 40 seconds at 25.degree. C., measured in a DIN
cup having a flow orifice of 4 mm. The solids content of this
diluted resin solution is determined by evaporation at 120.degree.
C. for 60 minutes.
The resin solution is applied by spray application to a steel
sheet, using one and a half cross-coats and exposing it to the air
for approx. 1 minute between each cross-coat. After exposing the
lacquered steel sheet to the air for 5 minutes, stoving is carried
out for 30 minutes at 120.degree. C. A smooth, blister-free and
crater-free lacquer with a dry film layer thickness of 70 to 80
.mu.m is obtained.
A reactive lacquer consisting of 70% by weight of copolymer, which
corresponds to 87.6 g of the copolymer 2 (A) solution used, and 30%
by weight of triisocyanate, which corresponds to 40 g of the
triisocyanate described above, is prepared by mixing and is
diluted, as described above, and the solids content is determined
and a steel sheet is lacquered. After stoving, the lacquered steel
sheet exhibits no craters or blisters at a dry film layer thickness
of 70 to 80 .mu.m.
A reactive lacquer consisting of 82.0% by weight of copolymer 1,
which corresponds to 61.8 g of the copolymer 1 (A) solution used
and 18.0% by weight, corresponding to 11 g, of
3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, is
prepared by mixing and is diluted, as described above, to the same
viscosity with acetone and the solids content is determined and a
steel sheet is lacquered as described above. After stoving, the
lacquered steel sheet exhibits no crater-formation or blistering
and has a smooth surface with a dry film layer thickness of 70 to
80 .mu.m.
A reactive lacquer consisting of 82.0% by weight of copolymer 2
(A), which corresponds to 62.5 g of the copolymer 2 (A) solution
used, and 18.0% by weight, which corresponds to 11 g, of
3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, is
prepared by mixing and is diluted, as described above, with acetone
to the viscosity described above. The solids content of the resin
solution was determined and a steel sheet was lacquered and stoved
as indicated above. The lacquered sheet had a dry film layer
thickness of 80 .mu.m and gave a smooth, crater-free and
blister-free surface.
The known reactive lacquers, which have the percentages by weight
indicated in Table 4, are diluted in the same way with acetone to a
flow viscosity of 40 seconds at 25.degree. C., measured in a DIN
cup having a 4 mm flow orifice. The resin solutions are also
applied to steel sheets by spray application, using one and a half
cross-coats and exposing the sheets to air for approx. 1 minute in
each case after each half cross-coat. After the reactive lacquers
have been applied, the sheets are exposed to air for 5 minutes and
stoved for 30 minutes at 120.degree. C. At first, only films having
a dry film layer thickness of 40 to 50 .mu.m were obtained. The
surface exhibited many craters and blisters. If it is desired to
achieve layer thicknesses of 70 to 80 .mu.m of dry film with the
known reactive lacquers, the spray application process must be
increased to two and a half to three cross-coats. The films, which
were then stoved, exhibited an even more strongly marked blistering
and crater-formation than the films having lower dry film layer
thicknesses. In addition, the solids content of the diluted resin
solutions was determined as described above.
Additional advantages for the copolymer solutions used emerge
clearly from these comparison tests.
Table 1
__________________________________________________________________________
Comparison tests on the copolymers Copolymer 1 (A) which Comparison
Comparison Comparison Comparison is used Test 1 Test 2 Test 3 Test
4
__________________________________________________________________________
Determination of solids con- tent of the copolymer solutions at
120.degree. C. for 60 minutes 81% 50% 50% 80% 80% Appearance
Turbidity 1 2-3 4 3 5 of the copolymer Flocculation of solutions
solid constitu- ents 0 + 0 0 0 Solids content, determined at
120.degree. C. for 60 minutes, of the resin solutions which have
been diluted with xyl- ene to a flow viscosity of 25 seconds at
25.degree. C., meas- ured in a DIN cup having a 4 mm flow orifice
47% 37% 28% 38% 34% Viscosity, measured by the The vis- The vis-
Gardner-Holdt method at 23.degree.C., cosity is cosity is of the
resin solutions which higher higher have been diluted with ethyl-
than Z.sub.6 than Z.sub.6 glycol acetate to a solids Z.sub.2 -- --
content of 70% Assessment of gloss and pig- ment deposition in
black top lacquers 1 2-3 5 3 5
__________________________________________________________________________
Table 2 ______________________________________ Test of the
compatibility of the copolymers 1 (A) and 2 (A) which are used and
the Comparison copolymers 1 and 2, with the thermoplastic
copolymers 1 and 2 50% by 50% by weight of weight of 50% by 50% by
the copoly- the copoly- weight of weight of mer in mer in copoly-
copolymer Comparison Comparison mer 1 (A) copolymer 1 copolymer 2 2
(A) ______________________________________ 50% by weight of
thermoplastic copolymer 1 1 2-3 4-5 1 50% by weight of
thermoplastic copolymer 2 1 2-3 4-5 1
______________________________________ Test of appearance of film:
1 = highgloss film (highest value) 5 = matt film (lowest value)
Table 3
__________________________________________________________________________
Comparison tests on reactive lacquers consisting of combinations of
copolymer 1 (A) and the Comparison copolymers 1 and 2, with
triisocyanate 70% by weight of 77% by weight of 70% by weight of
copolymer 1 (A) which copolymer from Com- copolymer from Com- is
used and 30% by parison copolymer 1 parison copolymer 2 weight of
triisocya- and 23% by weight of and 30% by weight of nate
containing triisocyanate con- triisocyanate con- biuret groups
taining biuret groups taining biuret groups
__________________________________________________________________________
After stoving for 30 minutes at 120.degree. C., the films are
tested against 5 minutes expo- sure to acetone, applied by a
cottonwool Fairly strong pad Slight swelling swelling Slight
swelling Determination of "pot Rise in visocity Rise in viscosity
Rise in viscosity life" after storage for to 30 seconds to 45
seconds to 95 seconds 6 hours at 230.degree. C. Test of run-off
ten- At a dry film layer At a dry film layer At a dry film layer
dency and crater- thickness of 80 .mu.m, thickness of 50 to
thickness of 40 to formation of lacquer no run-off tendency 60
.mu.m, a high run-off 50 .mu.m, considerable combinations which are
and no crater- tendency; at 70 to 80 run-off tendency; pigmented
with titanium formation .mu.m, considerable at 50 to 60 .mu.m, con-
dioxide and have been crater-formation siderable crater- stoved for
30 minutes formation at 120.degree. C.
__________________________________________________________________________
Table 4 ______________________________________ Solids content, in %
by weight, Appearance of the of the films obtained diluted from the
reactive resin lacquers, after solutions stoving
______________________________________ Reactive lacquer consisting
At 70-80 .mu.m, no of 70% by weight of copolymer blistering or 1
(A) used according to the crater-formation invention and 30% by
weight of triisocyanate 67.5 Reactive lacquer consisting At 70-80
.mu.m, no of 70% by weight of copolymer blistering or 2 (A) used
according to the crater-formation invention and 30% by weight of
triisocyanate 70.2 Reactive lacquer consisting At 70-80 .mu.m, no
of 82.0% by weight of copoly- blistering or mer 1 (A) used
according to crater-formation the invention and 18.0% by weight of
isophorone diiso- cyanate.sup.+ 68 Reactive lacquer consisting At
70-80 .mu.m, no of 82.0% by weight of copoly- blistering or mer 2
(A) used according to crater-formation the invention and 18.0% by
weight of isophorone diiso- cyanate.sup.+ 72 Reactive lacquer
consisting At 40-50 .mu.m, blis- of 77% by weight of tering and
crater- Comparison copolymer 1 and formation 23% by weight of
triiso- At 70-80 .mu.m, cyanate 52 increased blistering and
crater-formation Reactive lacquer consisting At 40-50 .mu.m, con-
of 70% by weight of siderable blistering Comparison copolymer 2 and
and crater-formation 30% by weight of triiso- At 70-80 .mu.m, the
cyanate 47 whole film is full of blisters and craters Reactive
lacquer consisting At 40-50 .mu.m, blis- of 85.7% by weight of
tering and crater- Comparison copolymer 1 and formation 14.3% by
weight of isopho- At 70-80 .mu.m, rone diisocyanate.sup.+ 52.5
increased blistering and crater-formation Reactive lacquer
consisting At 40-50 .mu.m, con- of 82.0% by weight of siderable
blistering Comparison copolymer 2 and and crater-formation -18.0%
by weight of iso- At 70-80 .mu.m, 75% phorone diisocyanate.sup.+ 48
of the film is full of blisters and craters As can be seen from
Table 4, the reactive lacquers used according to the invention are
superior to the known reactive lacquers.
______________________________________ .sup.+
3Isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate
The following are examples of reactive melamine resins which can be
used: monomethylol-pentamethoxymethylenemelamine,
dimethylol-tetramethoxymethylenemelamine or
trimethylol-trimethoxymethylenemelamine, on their own or as
mixtures.
* * * * *